Williams was gunning for her 23rd Grand Slam title at the US Open -- that would have taken her past the record she shares with Steffi Graf -- when she was cut down by 11th-ranked Karolina Pliskova in the semis.

The Czech's victory ensured that Kerber, who had been snapping at Williams' heels for weeks, would rise to number one.

The German then went on to beat Pliskova in the final to claim her second Grand Slam title of the year.

Williams' slip from the number one spot in September also denied her a second record: the American veteran had topped the rankings for 186 weeks -- a run Graf also matched.

And that double slight is sure to motivate Williams' to come back strong, said Kerber.

"She will try to win some more Grand Slams and write history for sure," she said.

Williams pulled out of the Wuhan Open and next week's China Open in Beijing on Friday, almost guaranteeing that Kerber will end the year as world number one.

But the 28-year-old -- the oldest ever women's player to debut at the top of the rankings -- isn't letting the pressure of her new position get to her.

"The ranking... it's just a number," she said.

"I was always telling myself if that day will come... then that would happen, but (I was) not putting too much pressure on myself."

That was also a tip she was given by mentor Graf, who Kerber met for a few days in Las Vegas, where the tennis idol lives with her husband Andre Agassi, after her Australian Open triumph.

"Actually she was just telling me to enjoy everything, to work hard and believe in yourself. So actually nothing new but it's of course a little bit different to hear it from her," said Kerber.

For now, for the left-hander, the plan is more of the same.

"This is my game... this is also what brings me (to) where I am right now. I will not change it."